1. Field of the Invention
The present invention relates to a device for controlling the amount of the air taken in by an engine by electrically controlling the throttle valve through a throttle actuator. More particularly, the invention relates to a device for controlling the amount of the air taken in by an engine, for improving the starting performance of when the accelerator pedal is depressed from the idling state.
2. Prior Art
There has heretofore been known a device for controlling the amount of the air taken in by the engine by controlling the throttle valve through a throttle actuator as disclosed in, for example, Japanese Patent Laid-Open No. 1-167438.
The conventional device for controlling the amount of the air taken in by the engine will be described below with reference to the drawings.
FIG. 6 is a block diagram schematically illustrating the constitution of the conventional device for controlling the amount of the air taken in by the engine, and wherein an accelerator pedal 1 operated by a driver is provided with an accelerator opening degree detection means 2 and an idle detection means 3.
The accelerator opening degree detection means 2 detects the opening degree of the accelerator pedal 1 as an accelerator opening degree .alpha..
The idle detection means 3 detects an idle signal D that corresponds to the fully closed position of the accelerator pedal 1.
The engine 4 is provided with an intake pipe 5 which includes a throttle valve 6 for adjusting the amount of the air Qa taken in by the engine 4.
The throttle valve 6 is driven by a throttle actuator 7. Further, the throttle valve 6 is provided with a throttle opening degree detection means 8 for detecting the opening degree of the throttle valve 6 as a throttle opening degree .theta..
A throttle control means 10 comprising a microcomputer operates a target throttle opening degree .theta.o based on the throttle opening degree .theta., accelerator opening degree .alpha. and idle signal D.
The throttle control means 10 receives not only the throttle opening degree .theta. but also the data from various other kinds of sensors (not shown) that detect the operation conditions of the engine 4, and operates the target throttle opening degree .theta.o.
In this case, the throttle control means 10 produces, as a final target throttle opening degree .theta.o, either a target throttle opening degree corresponding to the accelerator opening degree .alpha. or the target throttle opening degree at the time of ISC feedback corresponding to the idle signal D whichever is larger.
The throttle actuator 7 is driven by the throttle control means 10 and opens or closes the throttle valve 6 so that the throttle opening degree .theta. comes into agreement the target throttle opening degree .theta.o.
Thus, the throttle valve 6 is adjusted to the target throttle opening degree .theta.o permitting the air to be taken in by a required amount Qa by the engine 4.
That is, during the normal operation, the intake air amount Qa is adjusted by a target throttle opening degree .theta.o that corresponds to the accelerator opening degree .alpha. and during the idling operation (during the ISC feedback operation), the intake air amount Qa is adjusted by a target throttle opening degree .theta.o required for maintaining the idling speed.
When the driver depresses the accelerator pedal 1 from the idling state to start the vehicle, however, the throttle valve 6 has already been adjusted to the target throttle opening degree .theta.o for idling. In practice, therefore, the accelerator pedal is ineffectively depressed until the target throttle opening degree corresponding to the accelerator opening degree .alpha. (depressed amount) exceeds the throttle opening degree of during the idling, and it is not allowed to start the vehicle.
This is because in the conventional device, when the target throttle opening degree corresponding to the accelerator opening degree .alpha. becomes greater than the throttle opening degree of during the idling as a result of depressing the accelerator pedal 1, the throttle valve 6 is controlled being switched over to the target throttle opening degree .theta.o that corresponds to the accelerator opening degree .alpha..
According to the conventional device for controlling the amount of the air taken in by the engine as described above, the amount of depressing the accelerator pedal is not reflected by the throttle opening degree .theta. unless the target throttle opening degree .theta.o of when the accelerator pedal 1 is depressed reaches the throttle opening degree of during the idling, leaving a problem in that the driver feels a delay in the response after having depressed the accelerator pedal.